Gephyromantis portonae sp. nov. (lineage D)

Vences, Miguel, Koehler, Joern, Crottini, Angelica, Hofreiter, Michael, Hutter, Carl R., du Preez, Louis, Preick, Michaela, Rakotoarison, Andolalao, Rancilhac, Lois, Raselimanana, Achille P., Rosa, Goncalo M., Scherz, Mark D. & Glaw, Frank, 2022, An integrative taxonomic revision and redefinition of Gephyromantis (Laurentomantis) malagasius based on archival DNA analysis reveals four new mantellid frog species from Madagascar, Vertebrate Zoology 72, pp. 271-309 : 271

Gephyromantis portonae sp. nov. (lineage D)

Holotype.

ZSM 115/2021 (ACZCV 0032), adult male, from Sahaïndrana campsite (17.8971°S, 049.1991°E, ca. 239 m a.s.l.), Betampona Strict Nature Reserve, Antsinanana Region, eastern Madagascar, collected on 6 November 2013 by A. Crottini, D. Salvi, E. Scanarini , and J.H. Velo.

Paratypes.

ZSM 118/2021 (ACZCV 0223), adult female, from Vohitsivalana campsite (17.8826°S, 049.2056°E, ca. 497 m a.s.l.), Betampona Strict Nature Reserve, Antsinanana Region, eastern Madagascar, collected on 16 November 2013 by A. Crottini, D. Salvi, E. Scanarini , and Georges; ZSM 116/2021 (ACZCV 0030), adult female, from Sahaïndrana campsite (17.8961° S, 049.1995° E, ca. 240 m a.s.l.), Betampona Strict Nature Reserve, collected on 6 November 2013 by A. Crottini, D. Salvi, E. Scanarini , and J.H. Velo; ZSM 117/2021 (ACZCV 0025), adult male, from Sahaïndrana campsite (17.8945° S, 049.1988° E, ca. 349 m a.s.l.), Betampona Strict Nature Reserve, collected on 6 November 2013 by A. Crottini, D. Salvi, E. Scanarini , and J.H. Velo; MRSN A6263 (FAZC 13518), adult female, from Sahambendrana campsite (17.8984°S, 049.2154°E, ca. 429 m a.s.l.), Betampona Strict Nature Reserve, collected on 7 February 2007 by G.M. Rosa, and F. Andreone; MRSN A6319 (FAZC 13469), adult male, from Piste Fontsimavo (17.9264°S, 049.2083°E, ca. 220 m a.s.l.), Betampona Strict Nature Reserve, collected on 3 February 2007 by G. M. Rosa; UADBA uncatalogued (ACZCV 0069), adult individual (unsexed), from Piste Fontsimavo (17.9186°S, 049.2103°E, ca. 256 m a.s.l.), Betampona Strict Nature Reserve, collected on 11 November 2013 by A. Crottini, D. Salvi, E. Scanarini , Georges, G. M. Rosa, D.J. Harris, M. Randriamialisoa, and H. Lava; UADBA uncatalogued (ACZCV 0031), juvenile, from Sahaïndrana campsite, Betampona Strict Nature Reserve, collected on 7 November 2013 by A. Crottini, D. Salvi, E. Scanarini , and J.H. Velo; UADBA uncatalogued (ACZCV 0024), adult individual (unsexed), from Sahaïndrana campsite, Betampona Strict Nature Reserve, collected on 5 November 2013 by A. Crottini, D. Salvi, E. Scanarini , and J.H. Velo.

Etymology.

The specific epithet is a matronym for Ingrid Porton, our dear friend and colleague. Ingrid is a primatologist and Vice-Chair of Madagascar Fauna and Flora Group, and this honor is a recognition of her continuous support to the study of the unique biodiversity of Betampona Strict Natural Reserve, and her overall commitment to the conservation of Malagasy ecosystems.

Diagnosis.

A member of the subfamily Mantellinae based on the presence of intercalary elements between terminal and subterminal phalanges of fingers and toes (verified externally), and on the absence of nuptial pads and presence of femoral glands in males. Assigned to the subgenus Gephyromantis Laurentomantis in the genus Gephyromantis based on the strongly tubercular dorsal skin, absence of foot webbing, completely connected lateral metatarsalia, and molecular phylogenetic relationships. The new species differs from all nominal species of the subgenus Gephyromantis Laurentomantis as follows: From G. horridus by smaller body size (male SVL 22.4-22.9 mm vs. 33.5 mm), and absence of a dorsal pattern of two blackish transverse patches (vs. presence); from G. ranjomavo by the absence of light brown to orange-brown color covering limbs dorsally (vs. presence), a slightly smaller body size (male SVL 22.4-22.9 mm vs. 23.5-28.1 mm) and absence of a tibial gland (vs. presence); from G. striatus by absence of a vertebral stripe posteriorly on dorsum (vs. presence); from G. malagasius (as redefined herein) by absence of a distinct bluish gray pattern on a dark venter (vs. presence); from G. marokoroko by a more coarsely tubercular dorsal skin, presence of red color ventrally on limbs (vs. absence), absence of orange spots and vermiculations on dorsum (vs. presence), and absence of gray to whitish color on vocal sac (vs. presence). Furthermore, differing from all the aforementioned species (with the exeption of G. fiharimpe ) by the presence of bright red color in the inguinal region and ventrally on limbs and on a small portion of posterior belly in life (vs. absence), and by a substantial genetic divergence (>6% uncorrected pairwise distance in the 16S gene).

According to the molecular phylogeny, G. portonae sp. nov. is related to G. fiharimpe , G. matsilo , and G. oelkrugi described above, but appears to be the genetically most divergent species of this complex, possibly representing the sister taxon of a clade composed by the other three species. It differs from G. fiharimpe by the absence of a tibial gland (vs. presence), a more strongly tubercular dorsal skin, and brighter red ventral color (vs. less bright light red color), and an uncorrected 16S genetic distance of 6.1-8.1%; from the sympatric G. matsilo by third toe distinctly longer than fifth (vs. of similar length or slightly longer) and an uncorrected 16S genetic distance of 5.9-7.3%; and from G. oelkrugi by a dorsal skin composed of mostly rather large and rounded tubercles (vs. equally prominent but smaller and more pointed tubercles), and an uncorrected 16S genetic distance of 5.1-7.5%.

Description of the holotype.

Adult male in good state of preservation (Fig. 18 ), skin around left femoral gland cut for internal examination of gland. SVL 22.9 mm, for other measurements see Table 1 . Body slender; head longer than wide, as wide as body; snout rounded in dorsal view, subacuminate in lateral view; nostrils directed laterally, slightly protuberant, much nearer to tip of snout than to eye; canthus rostralis rather indistinct, slightly concave; loreal region slightly concave; tympanum distinct, rounded, 50% of eye diameter; supratympanic fold not recognizable; tongue ovoid, distinctly forked posteriorly; vomerine teeth weakly recognizable, but present in two small aggregations posteromedially to choanae; choanae rounded; maxillary teeth present. Dermal fold along the lower jaws (the inflatable parts of the vocal sac) not recognizable. Arms slender, subarticular tubercles single; outer and inner metacarpal tubercles distinct; fingers without webbing; relative length of fingers 1 <2 <4 <3, second finger distinctly shorter than fourth finger; finger discs distinctly enlarged; nuptial pads absent. Hindlimbs slender; tibiotarsal articulation reaching anterior corner of eye when hindlimb is adpressed along body; lateral metatarsalia connected; inner metatarsal tubercle distinct, outer metatarsal tubercle small but distinct; webbing between toes absent; relative toe length 1 <2 <5 <3 <4. Third toe distinctly longer than fifth toe. Toe discs enlarged. Skin on upper surface coarsely granular, with a few small ridges and numerous large tubercles on head, eyes, and dorsum. Ventral skin smooth on throat, chest and limbs, granular on posterior belly. Femoral glands well delimited and large, with seven large gland granules visible both in external and internal view. No tibial gland.

After eight years in preservative, dorsal coloration of head and body dark brown, washed with lighter brown color especially on the large tubercles. Darker brown crossbands on hind- and forelimbs. Ventral and posterodorsal surface of thigh with larger whitish/cream areas, which were presumably reddish in life. Ventrally, throat light brown to grayish with a few small light spots; chest brown; belly marbled with brown and light color.

Variation.

The specimens examined and photographed all agree well with each other in external morphology. Several photographed individuals have very large and coarse dorsal tubercles, of less spiny appearance compared to G. oelkrugi and G. matsilo (see especially Fig. 24A , but also 24E-G). Tibial glands are absent in all specimens. The two females are distinctly larger than the two males for which measurements are available (25.1-26.1 vs. 22.4-22.9).

Call.

Although the advertisement call has never been recorded and analysed, one male has been heard calling. Call sounded unmotivated with low amplitude notes.

Distribution and natural history.

Based on genetically verified records, the distribution area is restricted to (1) Sahafina and (2) Betampona. Calling males were observed in Betampona in a muddy bank close to slow running brooks, but the species is often encountered on the leaflitter in dense forest, along slopes and ridges of steep hills, far from water. The tadpole is unknown. A poorly known species apparently restricted to lowland rainforest habitat ranging from 200 m a.s.l. to approximately 500 m a.s.l. of elevation.

Figures

Figure 18. Preserved holotype specimens of the four new Gephyromantis species in dorsal and ventral view. A, B G. matsilo sp. nov. (lineage A), ZSM 711 / 2009 (ZCMV 7234) from Ambatoroma, Befanjana Forest. C, D G. fiharimpe sp. nov. (lineage B), ZSM 164 / 2016 (FGZC 5181) from Mandraka. E, F G. oelkrugi sp. nov., ZSM 314 / 2010 (FGZC 4220) from Ambodivoangy. G, H G. portonae sp. nov. (lineage D), ZSM 115 / 2021 (ACZCV 0032) from Betampona.

Figure 24. Specimens of Gephyromantis portonae sp. nov. (lineage D) in life, all from Betampona. A, B Specimen ACZCV 1216. C Specimen ACZCV 1215. D Specimen ACZCV 1311. E Specimen ACZCV 1353. F Specimen ACZCV 1350. G Specimen ACZCV 1358. Not to scale.